Mutations in the DNMT3A DNA methyltransferase in acute myeloid leukemia patients cause both loss and gain of function and differential regulation by protein partners
Mutations in the DNMT3A DNA methyltransferase in acute myeloid leukemia patients cause both loss and gain of function and differential regulation by protein partners
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DOI：
10.1074/jbc.ra118.006795
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发表时间：
2019-03-29
影响因子：
4.8
通讯作者：
Reich, Norbert O.
中科院分区：
文献类型：
--
作者：
Sandoval, Jonathan E.;Huang, Yung-Hsin;Reich, Norbert O.
真核生物的DNA甲基化通过调控癌基因和肿瘤抑制基因的表达来防止基因组不稳定。从头DNA甲基转移酶基因DNA甲基转移酶3（DNMT3A）的突变与急性髓系白血病（AML）患者预后不良之间存在强相关性，这凸显了DNA甲基化失调的负面影响。我们在此表明，临床观察到的DNMT3A突变会显著改变酶活性，包括导致人类细胞周期蛋白依赖性激酶抑制剂2B（CDKN2B或p15）基因启动子6倍高甲基化和3倍低甲基化的突变。我们的研究结果为临床上观察到的AML中p15甲基化的异质性提供了见解。细胞遗传学正常的AML（CN - AML）占所有AML病例的40% - 50%，是表观遗传学差异最大的AML亚型，在非CpG DNA甲基化方面有明显变化。我们鉴定出了一组DNMT3A突变，这些突变使该酶进行非CpG甲基化的能力增强2 - 8倍。其中许多突变定位于已知与对AML有影响的蛋白质相互作用的DNMT3A区域，比如胸腺嘧啶DNA糖基化酶（TDG）。通过对TDG - DNMT3A相互作用的功能定位，我们提供证据表明TDG和类DNMT3（DNMT3L）结合DNMT3A的不同区域。此外，DNMT3A突变导致TDG和DNMT3L影响DNMT3A功能的能力发生多种变化。对其中一种DNMT3A突变（S714C）进行的基于细胞的研究重复了酶学研究结果，并揭示该突变导致全基因组甲基化显著缺失。总之，DNMT3A突变会导致活性水平、与表观遗传机制组件的相互作用以及细胞变化呈现多样性。
Eukaryotic DNA methylation prevents genomic instability by regulating the expression of oncogenes and tumor-suppressor genes. The negative effects of dysregulated DNA methylation are highlighted by a strong correlation between mutations in the de novo DNA methyltransferase gene DNA methyltransferase 3 (DNMT3A) and poor prognoses among acute myeloid leukemia (AML) patients. We show here that clinically observed DNMT3A mutations dramatically alter enzymatic activity, including mutations that lead to 6-fold hypermethylation and 3-fold hypomethylation of the human cyclin-dependent kinase inhibitor 2B (CDKN2B or p15) gene promoter. Our results provide insights into the clinically observed heterogeneity of p15 methylation in AML. Cytogenetically normal AML (CN-AML) constitutes 40-50% of all AML cases and is the most epigenetically diverse AML subtype with pronounced changes in non-CpG DNA methylation. We identified a subset of DNMT3A mutations that enhance the enzyme's ability to perform non-CpG methylation by 2-8-fold. Many of these mutations mapped to DNMT3A regions known to interact with proteins that themselves contribute to AML, such as thymine DNA glycosylase (TDG). Using functional mapping of TDG-DNMT3A interactions, we provide evidence that TDG and DNMT3-like (DNMT3L) bind distinct regions of DNMT3A. Furthermore, DNMT3A mutations caused diverse changes in the ability of TDG and DNMT3L to affect DNMT3A function. Cell-based studies of one of these DNMT3A mutations (S714C) replicated the enzymatic studies and revealed that it causes dramatic losses of genome-wide methylation. In summary, mutations in DNMT3A lead to diverse levels of activity, interactions with epigenetic machinery components and cellular changes.